Surgery, more specifically orthopedic surgery, often requires the surgeon to apply significant forces to the anatomy in order to achieve a desired result. Insertion of medical devices, particularly orthopedic, typically involves repetitive low-frequency and high magnitude forces, commonly from a mallet or hammer. These high peak impact forces predispose the bone or soft tissue to mechanical failure or injury. Furthermore, high sudden peak forces make it more difficult to center the tool or implant.
For example, a surgeon may need to remove bony anatomy by chiseling. Chiseling typically requires at least two tools: a chisel with one bladed end perpendicular to the long axis of the instrument and the opposite end formed as a striking surface, and mallet used to apply force to the striking surface of the first tool.
In another application, a surgeon may need to impact a device in order to modify the anatomy to receive an implantable device. In the case of an orthopedic hip implant, a surgeon may repeatedly impact a broaching device to create the desired cavity within a femur. After an implantable device has been inserted, further impact may be necessary to position the device in its desired location or secure it in place.
In another application, a surgeon may need to insert a device into the anatomy. In orthopedics, examples include but are not limited to hip stems, knee replacements, shoulder replacements and various spinal devices such as interbody spacers, artificial disc replacements, interspinous devices and longitudinal members.
However, challenges exist when impacting or inserting devices, include surgeon fatigue, harm to the patient, harm to the device, whether it be the instrument or implant, and the need for multiple types of impactors or inserters depending on the type of surgery being performed.
The act of repeated striking an instrument with a mallet requires strength, endurance and accurate placement. In longer procedures, this activity could prematurely fatigue the user. Furthermore, when impacting with greater force or amplitude, the risk of harming the patient increases. In the example of hip replacement surgery, inserting a femoral stem under great force could fracture the femur. High amplitude impacting under lower frequency could also damage a medical implant. In the example of an Anterior Lumbar Interbody Fusion (ALIF) device, high amplitude impact forces could break the implantable device. Finally, in some instrument sets, each sample inserter may be a stand-alone device which adds weight, bulk and cost to the set. A mallet alone typically adds 2-5 pounds of weight to an instrument set.
Therefore, a need exists for a medical device impactor and inserter operable to apply consistent, controlled impact at a desired amplitude and frequency.